This invention relates to a process and a device for cleaning a spinning unit of an open-end friction spinning machine of the type having spinning units containing in each case two friction rollers that are drivable in the same rotational direction and are arranged next to one another to form a wedge-shaped gap serving as the yarn forming point or region. During the normal spinning operation, fed fibers and a forming yarn are maintained in the wedge-shaped gap by forces produced by at least one suction device acting at the wedge-shaped gap and by the friction of the rollers.
Within the spinning unit of the open-end friction spinning machine, deposits of flying fiber material, fiber residues, fiber dust and similar substances may be made which are contained in the fed fiber material and the fiber material to be processed. In particular, such deposits may adhere to the cover or shell surfaces of the friction rollers. Especially in the case of a yarn breakage when the forming yarn can no longer be withdrawn, despite the stopping of the feeding device after the yarn breakage, single fibers are continued to be fed by the feeding and opening device which are deposited in the wedge-shaped gap and remain there. As a result, a piecing process for eliminating the yarn breakage may be impaired. It is therefore necessary, from time to time and especially after a yarn breakage, to clean the spinning unit, especially in the area of the friction rollers. In order to be able to clean the rollers, it is disclosed in European Published Unexamined Patent Application (EP-OS) 52 412 to support the rollers independently from one another in such a way that one roller can be moved away from the other roller. Thereafter a manual cleaning can take place. Such a cleaning process is awkward and is difficult to carry out, especially by an automatic cleaning device. In addition, it is disadvantageous with respect to achieving an error free spinning result to arrange one of the two rollers in a movable bearing because then the narrow distance between the rollers can be maintained precisely only at considerable expenditure.
The invention is based, at least in part, on the objective of providing a process and a device of the above-mentioned type which is suitable for an automated working process and by means of which the rollers, especially in the area of the wedge-shaped gap, can be subjected to a reliable cleaning.
This objective is achieved according to the invention by providing that in the area of the wedge-shaped gap, a device for carrying out the cleaning process is applied, and that during the cleaning the yarn and fiber holding forces aimed into the wedge-shaped gap during normal spinning operation are removed or at least partially reduced. Especially by the removal or at least by the reduction of the forces acting at the wedge-shaped gap, dirt and especially also fiber residues can be removed from the area of the wedge-shaped gap in a simple manner.
According to certain preferred embodiments of the invention, it is provided that at least the roller rotating into the wedge-shaped gap during normal spinning operations is stopped during the cleaning. As a result, the conveying effect of this roller is interrupted so that fibers or fiber residues existing in the wedge-shaped gap can be carried out of the wedge-shaped gap by the second roller to the extent it continues ro run, so that these fibers or fiber residues can be grasped and carried away easily by a cleaning device. An especially advantageous embodiment of the invention provides that the roller rotating into the wedge-shaped gap during the spinning operation is, during the cleaning, rotated at least temporarily against its normal spinning operational rotating direction. This has the result that residues located in the wedge-shaped gap are at least moved slightly out of the wedge-shaped gap, since both rollers now rotate out of the wedge-shaped gap. The residues are therefore not jammed into the wedge-shaped gap. The residues are therefore not jammed into the wedge-shaped gap so that they can be removed relatively easily.
According to a further aspect of certain preferred embodiments of the invention, it is provided that during the cleaning, the effect of the suction device is turned off or at least reduced. This also at least reduces the forces affecting the dirt and residues in the area of the wedge-shaped gap, so that the removal of this dirt and these residues is simplified.
According to a further aspect of certain preferred embodiments of the invention, it is provided that the area of the wedge-shaped gap is sucked off (vacuum cleaned) and/or brushed off from the outside. This ensures a reliable cleaning of the rollers, during which parts adhering to the rollers are also removed. In this case, is especially advantageous if one or both rollers during the cleaning is/are driven with an alternating rotating direction.
In certain preferred embodiments of the invention, a device for the cleaning of a spinning unit is provided where a maintenance of servicing apparatus is provided that can be moved along the open-end friction spinning machine and can be applied to a spinning unit. The servicing apparatus contains a cleaning device that can be applied to the area of the wedge-shaped gap of the rollers of this spinning unit, and is equipped with means for removing or at least reducing the yarn and fiber holding forces acting at the wedge-shaped gap during the normal spinning operation. This servicing apparatus which, in particular can also contain the means required for an automatic piecing process after a yarn breakage, carries out the cleaning process without having to rely on the care of the operating personnel, especially removing reliably the residues or dirt located in the area of the wedge-shaped gap.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, embodiments in accordance with the present invention.